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Lucent Technologies Inc.
Preliminary Data Sheet
August 2000
ORCA Series 4 FPGAs
Special Function Blocks
(continued)
ORCABoundary-Scan Circuitry
The ORCA Series boundary-scan circuitry includes a
test access port controller (TAPC), instruction register
(IR), boundary-scan register (BSR), and bypass regis-
ter. It also includes circuitry to support the 18 pre-
defined instructions.
Figure 27 shows a functional diagram of the boundary-
scan circuitry that is implemented in the ORCA Series.
The input pins’ (TMS, TCK, and TDI) locations vary
depending on the part, and the output pin is the dedi-
cated TDO/RD_DATA output pad. Test data in (TDI) is
the serial input data. Test mode select (TMS) controls
the boundary-scan test access port controller (TAPC).
Test clock (TCK) is the test clock on the board.
The BSR is a series connection of boundary-scan cells
(BSCs) around the periphery of the IC. Each I/O pad on
the FPGA, except for CCLK, DONE, and the boundary-
scan pins (TCK, TDI, TMS, and TDO), is included in
the BSR. The first BSC in the BSR (connected to TDI)
is located in the first PIO I/O pad on the left of the top
side of the FPGA (PTA PIO). The BSR proceeds clock-
wise around the top, right, bottom, and left sides of the
array. The last BSC in the BSR (connected to TDO) is
located on the top of the left side of the array (PL1D).
The bypass instruction uses a single FF, which resyn-
chronizes test data that is not part of the current scan
operation. In a bypass instruction, test data received on
TDI is shifted out of the bypass register to TDO. Since
the BSR (which requires a two FF delay for each pad)
is bypassed, test throughput is increased when devices
that are not part of a test operation are bypassed.
The boundary-scan logic is enabled before and during
configuration. After configuration, a configuration
option determines whether or not boundary-scan logic
is used.
The 32-bit boundary-scan identification register con-
tains the manufacturer’s ID number, unique part num-
ber, and version (as described earlier). The
identification register is the default source for data on
TDO after RESET if the TAP controller selects the shift-
data-register (SHIFT-DR) instruction. If boundary scan
is not used, TMS, TDI, and TCK become user I/Os, and
TDO is 3-stated or used in the readback operation.
An optional USERCODE is available. The USERCODE
is a 32-bit value that the user can set during device
configuration and can be written to and read from the
FPGA via the boundary-scan logic.